Why does panel balancing matter?

On a 120/240 V single-phase system the shared neutral carries only the difference between the two hot legs. Balancing the 120 V loads minimizes neutral current, reduces voltage imbalance between legs, and frees up usable panel capacity so each leg is loaded evenly.

How is the neutral current calculated?

The tool sums the VA on leg A and leg B, converts each to amperes at 120 V, and takes the absolute difference. That difference is the current returning on the shared neutral. When the legs are perfectly balanced the neutral current approaches zero.

Do 240 V circuits affect the balance?

No. A 240 V two-pole circuit draws equal current from both hot legs and its return cancels in the neutral, so it never contributes to imbalance. The tool counts it toward total panel capacity but excludes it from the balance percentage.

What imbalance percentage is acceptable?

A common target is to keep the two legs within about 10% of each other. Beyond that, the heavier leg can approach its capacity while the lighter leg sits idle, and the elevated neutral current and voltage difference can affect sensitive equipment.

How does the rebalancer decide where circuits go?

It sorts the 120 V circuits from largest to smallest and assigns each to whichever leg is currently lighter, a greedy strategy that produces a near-optimal split. It then reports how many circuits would move and the imbalance you would reach.

What is the Single-Phase Panel Load Balancing Calculator?

Takes a circuit-by-circuit load list with leg assignments and reports per-leg totals, neutral current, and imbalance percentage, then suggests circuit reassignments to bring a 120/240 V single-phase panel within a 10% balance target. It runs free in your browser on Gera Tools, with nothing uploaded.

Single-Phase Panel Load Balancing Calculator

Name: Single-Phase Panel Load Balancing Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Get one useful tool a week

Like this tool? Enter your email and we'll send you one genuinely useful Gera tool a week — plus a link to come back to this one. No spam, one-click unsubscribe any time.

On a 120/240 V single-phase panel the shared neutral carries only the difference between the two hot legs, so spreading the 120 V loads evenly minimizes neutral current and balances the panel. This calculator takes your circuit list, reports per-leg totals and the neutral imbalance, and suggests a reassignment that brings the panel within a 10% balance target.

How it works

Each circuit’s VA is summed by leg, converted to amps, and compared:

leg A amps   = sum of leg-A VA / 120
leg B amps   = sum of leg-B VA / 120
neutral amps = | leg A amps − leg B amps |
imbalance %  = | leg A VA − leg B VA | / max(leg A VA, leg B VA) × 100

A 240 V two-pole circuit loads both legs equally and cancels in the neutral, so it is excluded from the imbalance figure. The rebalancer sorts the 120 V circuits largest-first and drops each onto the lighter leg, which closely approaches the best possible split.

Why a large imbalance matters in practice

When leg A consistently draws significantly more current than leg B, three things happen:

Elevated neutral current. The neutral wire carries the difference between the two legs continuously. An oversized neutral current can cause overheating if the neutral was sized for a more balanced load, and it produces voltage drop between the two 120 V legs.
Voltage imbalance. The heavier leg sees slightly lower voltage under load due to impedance, while the lighter leg sits higher. Sensitive equipment — particularly motor loads like refrigerators and HVAC units — can run hot or malfunction when leg voltages diverge by more than a couple of volts.
Wasted capacity. Half of your panel capacity is idle while the other half is under strain. Rebalancing lets you use the available capacity more evenly, which matters when adding new circuits.

Worked example

Leg A carries: kitchen outlets (2,400 VA) + living room (1,800 VA) + dryer circuit (0 VA, this is 240 V) = 4,200 VA

Leg B carries: bedroom outlets (900 VA) + bathroom (600 VA) + office (1,200 VA) = 2,700 VA

leg A amps   = 4,200 / 120 = 35 A
leg B amps   = 2,700 / 120 = 22.5 A
neutral amps = |35 − 22.5| = 12.5 A
imbalance %  = |4,200 − 2,700| / 4,200 × 100 ≈ 35.7%

Moving the living room circuit (1,800 VA) from leg A to leg B brings the totals to 2,400 VA and 4,500 VA — now leg B is heavier by 2,100 VA. Instead, move the office circuit (1,200 VA) from B to A: new totals are 5,400 VA and 1,500 VA — worse. Try a greedy approach: assign the largest single circuit (kitchen outlets at 2,400 VA) to the lighter leg. The rebalancer does this automatically, iterating through circuits largest-first until the split is as even as possible.

Tips for reading and acting on the result

Balance by running load (VA), not by breaker count. A single 20-amp kitchen circuit can outweigh five 15-amp bedroom circuits. When adding an EV charger (typically 7,200 VA at 240 V) or an electric range (typically 7,200–10,000 VA), those are 240 V loads and do not affect leg balance, but they add heavily to total panel capacity — check that the panel’s main breaker rating is not exceeded. Rebalance the panel each time a significant new 120 V load is added.